i recently put a 4.88 l/s third member into the back of the 85 so that we finally had matching front and rear gears. i droveit for about 3 days and everything seemed to be going fine until yesterday morning.
as i was driving to work, something didnt sound right but i payed no mind ot it as i had to crest an almost sheer vertical hill on the way to work. halfway up the hill the rear end started shuddering as though i was driving on a road filled with potholes, but that was no tthe case. i pulled over and looked at the third and saw that the nut that sits inside the flange where the driveshaft meets the pinion had backed itself off and the pinion had walked its way out and was not making contact with the ring inside the third. i was worried i might have sheared off teeth and done some major damage.
i pulled the rear shaft and drove it back home in 4 high and played with the rear a little bit....when i put the pinion back in where its supposed to sit, everything seems to behave as it should....there is a slight bit of play back and forth which it had when i first installed it, the limited slip is acting how it should....so i have two questons really, how should i proceed from this point...should i pull the third out and have a shop look at it (that would be the safe bet i know, but if i dont have to pull it then id rather not) and what would cause that nut to back off. there was the nut and a thick washer under it, but that is it. is a peice missing? possibly a washer with a notch to sit in that groove in there?

Nope....just a thick washer and a nut.....you need a local shop to check it out. The big nut should have been staked or loctited. Who worked on it last? Is this that Genuine Toyota Supra limited slip with genuine Yota special 488 gears? Or is it aftermarket 488 gears with a Tru-trac or TRD LSD?

Sounds like the nut was not "staked" after torqueing it to spec. You are supposed to use a punch to deform the lip of the nut into the grovve in the pinion shaft that you mentioned. The "stake" then prevents the nut from backing off. You can see where the stake used to be on this pinion flange photo below:

Came out of the rear of a 92 4Runner... all genuine Toyota. It's my truck and I'm not going to be happy if there is damage. <img src="/forums/images/graemlins/angry.gif" alt="" />


I'm not sure if he did that or not when putting it in... <img src="/forums/images/graemlins/zombie.gif" alt="" />

Well Monica....it sure does seem kinda strange that the nut decided to loosen up. That is just not common. It must have been dis-assembed in the past for some reason. In any event, that's bridge under the water so, at this point, just tightening it up and re-staking might work....but I think someone should put in a new crush sleeve or even better a solid collar. That requires complete dis-assembly. I do that kind of work, by the way. See my webpage. ZUK

Bummer.

If you have someone other than Zuk button that thing up, make sure they use Loctite AND ping the pinion nut.

well, it appears as though there was an attempt made at staking the nut, but it was a very poor one....my first thought was the small dent was due to some damage when it came off while driving....a few of the threads on the nut are damaged so i am going to have to get a new nut.

if there was damage to the guts of the third would it still behave normally or would there be any telltale signs. am i really stuck with going thru the whole process of pulling the thign again???

one more question, what are the chances that the nut off a stock 4.10 diff would be the same size as a 4.88 diff?

The companion flange nuts; including 4-cyl and V6 pinion and t-case flanges are all the same.

Well....when the pinion nut comes off....or just loosens up a little....I know the terrible noise that happens cause it happened a couple times to me back in 87....the end of the pinion teeth are basically grinding into the limited slip casing....even though the noise sounds like death it's probably doing nothing except cosmetic damage. Odds are in your favor no damage.
You can try a combination of blue loctite and staking...I personally would not hesitate re-using a damaged nut with Loctite. I suppose you wouldn't hurt it anymore if you tried snugging the nut and feel the companion flange rotational play....if it still feels loosey then tighten it more....then more ....then more...until it feels too tight(whatever too tight feels like) then back it off a little until it feels a bit loose and stake it. That's the quick fix. good luck. <img src="/forums/images/graemlins/kewl.gif" alt="" />

number one, thanx to all you fine fellas for responding with such good info, i sometimes take for granted the top notch advice i get from here.


secondly, two more questions, one just for my knowledge mostly.
1-so if i reused the original nut, there are two threads that are slightly bent where the nut was staked....when i thread it back on, that nut is made out of weaker material then the pinion itslef so it should align itself naturally right?

secondly, driving with the rear driveshaft disconnected in 4 high at 40 mph.....good idea or bad idea.

once again thanx!